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Re: convert to pixel to RA and DEC in degrees? [message #49555]

Thu, 03 August 2006 09:45

adisn123
Messages: 44
Registered: July 2006

Member

THank you all. It was a great help.
Craig Markwardt wrote:
> adisn123@yahoo.com writes:
>> Forgot one more thing.
>>
>> When applying "xyad" procedure to convert pixel coordinates to RA and
>> DEC,
>> the North direction of RA and DEC coords should align with the North
>> direction of pixel coords?
>
> It doesn't have to be aligned. It depends on how the telescope or
> camera was pointed.
>
>> If it is, then the image should be rotated in such a way that its North
>> in RA and DEC should
>> match with the North of pixel coords. I took a look at the image 's
>> header to look for how many degrees I should rotate such that they
>> align perfectly each other, but I can't find anything relevant to the
>> rotation degrees.
>
> Some FITS images have a CROTAn keyword. Others have a rotation
> matrix, which is stored in CDn_n, I believe. More info can be found
> here,
> http://fits.gsfc.nasa.gov/fits_wcs.html
>
> Craig
>
> --
> ------------------------------------------------------------ --------------
> Craig B. Markwardt, Ph.D. EMAIL: craigmnet@REMOVEcow.physics.wisc.edu
> Astrophysics, IDL, Finance, Derivatives | Remove "net" for better response
> ------------------------------------------------------------ --------------

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[Message index]

		Re: convert to pixel to RA and DEC in degrees? By: adisn123 on Thu, 03 August 2006 09:45
		Re: convert to pixel to RA and DEC in degrees? By: Craig Markwardt on Thu, 03 August 2006 07:12
		Re: convert to pixel to RA and DEC in degrees? By: Wayne Landsman on Wed, 02 August 2006 09:57
		Re: convert to pixel to RA and DEC in degrees? By: adisn123 on Wed, 02 August 2006 09:50

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